Certain image forming devices use an electrophotographic imaging process to develop toner images on a media sheet. The electrophotographic process uses a number of electrostatic voltage differentials to promote the transfer of toner from component to component. For example, a voltage vector may exist between a developer member and a latent image on a photoconductive element. This voltage vector helps promote the transfer of toner from the developer member to the latent image in a process that is sometimes called “developing the image.” A separate voltage vector may exist between the photoconductive element and a transfer member to promote the transfer of a developed image onto a substrate. In each instance, the toner transfer occurs in part because the toner itself is charged and is attracted to surfaces having an opposite charge or a lower potential.
Many toners comprise a single-component formulation. The term “single-component” is usually understood to mean that the toner does not have magnetic particle additives that are used in some two-component toner formulations to promote toner transfer. Despite the name, some single-component toner formulations include extra-particulate additives (EPA's) that improve fluidity and other printing properties. EPA's are bound to the surface of toner particles by mechanical, VanderWaals, and electrostatic forces. When toner containing these EPA's are conveyed past a biased component, the EPA's may separate from the toner under the influence of local electrostatic fields.
In certain instances, these separated EPA's can begin to accumulate over time to form a barrier that restricts toner flow resulting in undeveloped streaks in the final image. One area where this problem is particularly noticeable is in the region between a doctor element and a developer member. A doctor element in an electrophotographic device controls the thickness (and in some cases, the charge) of the layer of toner on a developing roller that ultimately develops a latent image. This region is problematic because the gap between the doctor element and the developing roller is small (i.e., on the order of a few toner particles). Thus, while EPA's may be small in comparison to the size of toner particles, the accumulation thereof may quickly result in degraded image quality.